This invention relates to web splicing for paper and the like, and more particularly to a concept involving splicing together the web from a fresh roll of paper and the web from a nearly spent roll of paper in a continuous paper web feeding operation.
The concepts of the invention can be utilized in connection with a large variety of devices where a web of paper or other material is continuously supplied. One such device can be a machine for wrapping boards with paper, such as in the present inventor's U.S. Pat. No. 3,590,552 issued July 6, 1971 and entitled "Automatic Panel Wrapping Machine." Another such device can be a corrugating machine.
In such machines, the paper supply comprises a pair of paper rolls which alternately feed a web of paper in continuous fashion to the machine input. When one roll is exhausted, the other roll is substituted. To prevent extensive down time, it has been found desirable to quickly splice the web of a fresh roll onto the web of a nearly exhausted roll.
The machine of aforementioned U.S. Pat. No. 3,590,552 includes such a device. In that patent, the task of splicing two supply webs together was accomplished by forcing an eccentric roll against an idler roll, with the paper traveling between the rolls, and with the movement of the eccentric roll automatically causing a knife to sever the web of the nearly exhausted roll.
In other known devices, a paper roll brake has been used to bring the exhausted paper roll to a stop for web splicing. In addition, the splicing has been accomplished by pressing the two webs together between a pair of splice sealing rolls which form a nip, and by the use of an adhesive between the webs. It is further known to feed the running or spliced web continuously over an idler roll disposed downstream from the splicing apparatus, and then to an accumulator or dancer roll, and subsequently to the machine which is to utilize the paper web. See U.S. Pat. No. 3,841,944 to Harris, Jr. In addition, it has been proposed to apply an adjesive strip to a new web attached to a splice sealing roll and then to rotate this roll to bring the adhesive into position for a horizontal engagement with the expiring roll. See U.S. Pat. No. 3,837,954 to Nudinger et al.
Heretofore, it has been found difficult to get the spliced web, which has momentarily been stopped, up to normal speed as quickly as possible before the excess web at the accumulator dancer roll runs out. Furthermore, it has been found that with at least some of the known structures, misalignment between the paper webs which may occur between the paper supply rolls and the splicing rolls may continue on downstream up to and past the idler roll, thereby causing tensions to develop which will rip or tear the paper web.
It is the task of the present invention to significantly reduce one or both of the above problems, and also to splice two webs together in an entirely new way so that the same splicer can be added to many types of web handling machines without major modification of the latter. Progress in the technical art of web splicing has therefor been accomplished.
In the form of the device shown, at least one movable splicer assembly is disposed adjacent a paper supply roll and which includes an idler roll, a paper stop device, a severing device and a splice sealing roll. When the assembly is disposed adjacent the nearly exhausted paper roll, the stop device is actuated to hold the outgoing web from moving, regardless of the existence or adequacy of a roll brake. When the assembly is disposed adjacent the spent roll, the stop device positively holds the paper for lead-edge cutting and trimming during set-up and keeps the paper in place until the splice is made. The splice sealing roll has provisions to guide a cutting tool for said lead-edge forming of the fresh web, and also for optimally locating the lead edge. A separate splicer assembly is disposed adjacent each of the pair of rolls, with the splice sealing rolls being engageable to form a nip for sealing the splice.
In accordance with one aspect of the invention, the fixed idler roll which is disposed at the discharge end of the splicing area and upstream of the accumulator dancer roll, is provided with a drive mechanism which includes a motor and which may include a selectively engageable clutch therebetween. At the time of the splice, the motor is driven to convert the idler roll into a driven capstan which accelerates the spliced web up to line speed; and thereafter the drive is disengaged. This substantially reduces the problem of exhaustion of the accumulator before the new web can be supplied.
In accordance with another aspect of the invention, driving of the idler roll after splicing will cause the capstan effect to pull the web forwardly, thus reducing problems caused by misalignment.